JP5557022B2 - Method for evaluating a copolymer for lithography - Google Patents

Description

  The present invention relates to a method for evaluating a copolymer for lithography.

In the manufacturing process of semiconductor elements, liquid crystal elements, etc., in recent years, pattern formation by lithography has been rapidly miniaturized. As a technique for miniaturization, there is a reduction in wavelength of irradiation light.
Recently, KrF excimer laser (wavelength: 248 nm) lithography technology has been introduced, and ArF excimer laser (wavelength: 193 nm) lithography technology and EUV excimer laser (wavelength: 13 nm) lithography technology for further shortening the wavelength have been studied. .
Further, for example, as a resist composition that can suitably cope with a shorter wavelength of irradiation light and a finer pattern, a polymer in which an acid-eliminable group is eliminated by the action of an acid and becomes alkali-soluble, and a photoacid generator A so-called chemically amplified resist composition containing the above has been proposed, and its development and improvement are underway.

As a chemically amplified resist polymer used in ArF excimer laser lithography, an acrylic polymer that is transparent to light having a wavelength of 193 nm has attracted attention.
For example, in the following Patent Document 1, (A) (meth) acrylic acid ester in which an alicyclic hydrocarbon group having a lactone ring is ester-bonded and (B) an acid can be eliminated as a monomer. (Meth) acrylic acid ester having an ester bond, and (C) a (meth) acrylic acid ester having a polar substituent and a hydrocarbon group or oxygen atom-containing heterocyclic group bonded to each other. Copolymers for resist are described.

By the way, it is important for the copolymer for resists to be able to form a favorable pattern using the resist composition containing this. Such a copolymer for resist is generally evaluated by a method of actually preparing a resist composition and measuring various development characteristics of the resist composition.
In Patent Documents 2 and 3 below, a resist using the resin is obtained from specific parameters obtained by dissolving a resin containing a resist copolymer in a resist solvent and measuring dynamic light scattering of the solution. A method for predicting the degree of occurrence of development defects, the degree of variation in pattern dimension (LER), or the degree of occurrence of foreign matter in the liquid is described.

JP 2002-145955 A JP-A-2005-091407 JP 2009-037184 A

As in Patent Documents 2 and 3, a method for evaluating the performance of a resist copolymer as a resist composition without actually preparing and developing a resist composition is simple. Since the influence of components other than the copolymer can be eliminated, it is useful as a method for strictly evaluating the performance of the copolymer itself.
However, the molecular weight distribution and composition distribution of next-generation resist copolymers are precisely controlled. When evaluating copolymers with slight structural differences and development characteristics obtained by such methods. However, in the method described in the above-mentioned patent document, there is a problem in detection accuracy, and a difference between the copolymers cannot be detected. Therefore, the present situation is that the evaluation method does not reflect the uniformity of dimensions corresponding to the fine pattern required for the next generation and the occurrence frequency of development defects.

  In addition, a copolymer for lithography other than the copolymer for resist, for example, a copolymer used for forming a thin film such as an antireflection film, a gap fill film, a top coat film or the like formed on an upper layer or a lower layer of a resist film in a lithography process. Similarly, for the coalescence, it is important whether or not the lithographic composition containing it has the performance (lithographic properties) for performing high-precision fine processing. And the method which can evaluate the performance when it is set as the composition for lithography of the copolymer for lithography without actually preparing the composition for lithography and performing a lithography process is desired.

  The present invention has been made in view of the above circumstances, and it is possible to evaluate the lithography characteristics of a lithographic copolymer as a lithographic composition without actually preparing the lithographic composition, and a resin. It is an object of the present invention to provide a method capable of strictly evaluating the resolution and uniformity of dissolution performance.

In order to solve the above problems, a first aspect of the present invention is a method for evaluating a copolymer for lithography, which includes the following steps.
(1) a step of preparing a test solution by dissolving a copolymer for lithography in a solvent;
(2) a step of measuring the scattering intensity in the particle size distribution of the test solution using a dynamic light scattering method;
(3) adding a poor solvent to the test solution and measuring a scattering intensity in a particle size distribution of the test solution after the poor solvent is added using a dynamic light scattering method;
(4) When the scattering intensity of an arbitrary peak (a) of the particle size distribution measured in the step (2) is used as a reference, the measurement is performed in the step (3) by adding a poor solvent. Obtaining a poor solvent addition amount required for the scattering intensity of the peak (a) to decrease to a predetermined intensity with respect to the reference;
(5) The process of evaluating the lithography characteristic of the composition containing the said copolymer for lithography by the difference in the said poor solvent addition amount.

According to the method of the present invention, the characteristics of a lithographic composition containing a lithographic copolymer can be evaluated without actually adjusting the lithographic composition.
In addition, according to the method of the present invention, by adding a poor solvent to relatively increase the concentration of the copolymer relative to the solution, a minute difference between the copolymers can be enlarged and detected. In this case, it is possible to compare copolymers having a minute difference that is almost the same as the accuracy and error of measurement, and high accuracy evaluation is possible.

  In the present specification, “(meth) acrylic acid” means acrylic acid or methacrylic acid, and “(meth) acryloyloxy” means acryloyloxy or methacryloyloxy.

<Copolymer for lithography>
The lithography copolymer to be evaluated in the present invention is not particularly limited as long as it is a copolymer used in the lithography process.
For example, it is used for forming a resist copolymer used for forming a resist film, an antireflection film (TARC) formed on the upper layer of the resist film, or an antireflection film (BARC) formed on the lower layer of the resist film. Examples thereof include a copolymer for antireflection film, a copolymer for gap fill film used for forming a gap fill film, and a copolymer for top coat film used for forming a top coat film.

  Examples of the copolymer for resist include a copolymer containing one or more structural units having an acid-eliminable group and one or more structural units having a polar group.

Examples of the copolymer for antireflection film include a structural unit having a light-absorbing group and an amino group, an amide group, a hydroxyl group, and an epoxy group that can be cured by reacting with a curing agent to avoid mixing with the resist film. And a copolymer containing a structural unit having a reactive functional group.
The light-absorbing group is a group having high absorption performance with respect to light in a wavelength region where the photosensitive component in the resist composition is sensitive. Specific examples include an anthracene ring, naphthalene ring, benzene ring, quinoline ring. , A group having a ring structure (which may have an arbitrary substituent) such as a quinoxaline ring and a thiazole ring. In particular, when KrF laser light is used as irradiation light, an anthracene ring or an anthracene ring having an arbitrary substituent is preferable, and when ArF laser light is used, a benzene ring or a benzene having an arbitrary substituent A ring is preferred.

Examples of the optional substituent include a phenolic hydroxyl group, an alcoholic hydroxyl group, a carboxy group, a carbonyl group, an ester group, an amino group, and an amide group.
Among these, those having a protected or unprotected phenolic hydroxyl group as the light absorbing group are preferable from the viewpoint of good developability and high resolution.
Examples of the structural unit / monomer having the light-absorbing group include benzyl (meth) acrylate and p-hydroxyphenyl (meth) acrylate.

As an example of a gap fill film copolymer, it has a suitable viscosity for flowing into a narrow gap, and reacts with a curing agent in order to avoid mixing with a resist film or an antireflection film. Examples include a copolymer containing a structural unit having a functional group, specifically, a copolymer of hydroxystyrene and a monomer such as styrene, alkyl (meth) acrylate, or hydroxyalkyl (meth) acrylate.
Examples of the copolymer for the topcoat film used for immersion lithography include a copolymer containing a structural unit having a carboxyl group, a copolymer containing a structural unit having a fluorine-containing group substituted with a hydroxyl group, and the like. .

  It is not easy to copolymerize these lithographic copolymers according to the molecular design, resulting in variations in molecular weight and monomer composition ratio. Even if the molecular design is the same, if the manufacturing method is different, the degree of variation in the molecular weight and the composition ratio of the monomers is different, and in the lithography process, the difference in performance can be caused only by the difference in the manufacturing method. According to the evaluation method of the present invention, the difference in performance due to such a difference in the production method can also be evaluated, so that the copolymer for lithography is preferred as the copolymer to be evaluated in the present invention.

<Copolymer for resist>
Hereinafter, the present invention will be described by taking a resist copolymer (hereinafter sometimes simply referred to as a copolymer) as a representative example of a lithography copolymer, but other lithographic copolymers are also applicable. it can.
The resist copolymer is not particularly limited as long as it is a copolymer used for forming a resist film.

Specifically, a resist copolymer containing at least one structural unit having an acid leaving group and at least one structural unit having a polar group is preferable. The resist copolymer is obtained by polymerizing a monomer mixture composed of one or more monomers having an acid leaving group and one or more monomers having a polar group.

[Structural Unit / Monomer Having Acid Leaving Group]
The “acid-leaving group” is a group having a bond that is cleaved by an acid, and a part or all of the acid-leaving group is eliminated from the main chain of the copolymer by cleavage of the bond. .
When used as a resist composition, a copolymer containing a structural unit having an acid-eliminable group is soluble in an alkali by an acid, and has an effect of enabling the formation of a resist pattern.
In view of sensitivity and resolution, the content of the structural unit having an acid leaving group is preferably 20 mol% or more, more preferably 25 mol% or more, of all the structural units constituting the copolymer. Moreover, 60 mol% or less is preferable from the point of the adhesiveness to a board | substrate etc., 55 mol% or less is more preferable, and 50 mol% or less is further more preferable.

  The monomer having an acid leaving group may be a compound having an acid leaving group and a polymerizable multiple bond, and known ones can be used. The polymerizable multiple bond is a multiple bond that is cleaved during the polymerization reaction to form a copolymer chain, and an ethylenic double bond is preferable.

Specific examples of the monomer having an acid leaving group include (meth) acrylic acid esters having an alicyclic hydrocarbon group having 6 to 20 carbon atoms and having an acid leaving group. It is done. The alicyclic hydrocarbon group may be directly bonded to an oxygen atom constituting an ester bond of (meth) acrylic acid ester, or may be bonded via a linking group such as an alkylene group.
The (meth) acrylic acid ester has an alicyclic hydrocarbon group having 6 to 20 carbon atoms, and a tertiary carbon atom at the bonding site with the oxygen atom constituting the ester bond of the (meth) acrylic acid ester. A (meth) acrylic acid ester having an alicyclic group or an alicyclic hydrocarbon group having 6 to 20 carbon atoms and a -COOR group (R may have a substituent) on the alicyclic hydrocarbon group. (Meth) acrylic acid ester in which a tertiary hydrocarbon group, a tetrahydrofuranyl group, a tetrahydropyranyl group, or an oxepanyl group is bonded directly or via a linking group is included.

In particular, in the case of producing a resist composition that is applied to a pattern forming method that is exposed to light having a wavelength of 250 nm or less, as a preferred example of a monomer having an acid leaving group, for example, 2-methyl-2- Adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, 1- (1′-adamantyl) -1-methylethyl (meth) acrylate, 1-methylcyclohexyl (meth) acrylate, 1-ethylcyclohexyl ( And (meth) acrylate, 1-methylcyclopentyl (meth) acrylate, 1-ethylcyclopentyl (meth) acrylate and the like.
As the monomer having an acid leaving group, one type may be used alone, or two or more types may be used in combination.

[Constitutional unit / monomer having a polar group]
The “polar group” is a group having a polar functional group or a polar atomic group. Specific examples include a hydroxy group, a cyano group, an alkoxy group, a carboxy group, an amino group, a carbonyl group, and a fluorine atom. A group containing a sulfur atom, a group containing a lactone skeleton, a group containing an acetal structure, a group containing an ether bond, and the like.
Among these, the resist copolymer applied to the pattern forming method that is exposed to light having a wavelength of 250 nm or less preferably has a structural unit having a lactone skeleton as the structural unit having a polar group. It is preferable to have a structural unit having a hydrophilic group.

(Constitutional unit / monomer having a lactone skeleton)
Examples of the lactone skeleton include a lactone skeleton having about 4 to 20 members. The lactone skeleton may be a monocycle having only a lactone ring, or an aliphatic or aromatic carbocyclic or heterocyclic ring may be condensed with the lactone ring.
When the copolymer includes a structural unit having a lactone skeleton, the content thereof is preferably 20 mol% or more of all structural units (100 mol%) from the viewpoint of adhesion to a substrate and the like, and 35 mol%. The above is more preferable. Moreover, from the point of a sensitivity and resolution, 60 mol% or less is preferable, 55 mol% or less is more preferable, and 50 mol% or less is more preferable.

  As a monomer having a lactone skeleton, a (meth) acrylic acid ester having a substituted or unsubstituted δ-valerolactone ring, a substituted or unsubstituted γ-butyrolactone ring is used because of its excellent adhesion to a substrate or the like. Preferably, at least one selected from the group consisting of monomers having it is preferred, and monomers having an unsubstituted γ-butyrolactone ring are particularly preferred.

Specific examples of the monomer having a lactone skeleton include β- (meth) acryloyloxy-β-methyl-δ-valerolactone, 4,4-dimethyl-2-methylene-γ-butyrolactone, β- (meth) acryloyl. Oxy-γ-butyrolactone, β- (meth) acryloyloxy-β-methyl-γ-butyrolactone, α- (meth) acryloyloxy-γ-butyrolactone, 2- (1- (meth) acryloyloxy) ethyl-4-butanolide , (Meth) acrylic acid pantoyl lactone, 5- (meth) acryloyloxy-2,6-norbornanecarbolactone, 8-methacryloxy-4-oxatricyclo [5.2.1.0 ^2,6 ] decane-3 -One, 9-methacryloxy-4-oxatricyclo [5.2.1.0 ^2,6 ] decan-3-one and the like. Examples of the monomer having a similar structure include methacryloyloxysuccinic anhydride.
Monomers having a lactone skeleton may be used alone or in combination of two or more.

(Structural unit / monomer having a hydrophilic group)
The “hydrophilic group” in the present specification is at least one of —C (CF ₃ ) ₂ —OH, a hydroxy group, a cyano group, a methoxy group, a carboxy group, and an amino group.
Among these, it is preferable that the copolymer for resist applied to the pattern formation method exposed with the light of wavelength 250nm or less has a hydroxyl group and a cyano group as a hydrophilic group.
The content of the structural unit having a hydrophilic group in the copolymer is preferably 5 to 30 mol%, more preferably 10 to 25 mol%, of the total structural units (100 mol%) from the viewpoint of resist pattern rectangularity. preferable.

  As the monomer having a hydrophilic group, for example, a (meth) acrylic acid ester having a terminal hydroxy group, a derivative having a substituent such as an alkyl group, a hydroxy group, or a carboxy group on the hydrophilic group of the monomer, Monomers having a cyclic hydrocarbon group (cyclohexyl (meth) acrylate, 1-isobornyl (meth) acrylate, adamantyl (meth) acrylate), tricyclodecanyl (meth) acrylate, dimethacrylate (meth) acrylate Cyclopentyl, 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, etc.) having a hydrophilic group such as a hydroxy group or a carboxy group as a substituent. Can be mentioned.

Specific examples of the monomer having a hydrophilic group include (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxy- (meth) acrylate. -Propyl, 4-hydroxybutyl (meth) acrylate, 3-hydroxyadamantyl (meth) acrylate, 2- or 3-cyano-5-norbornyl (meth) acrylate, 2-cyanomethyl-2-adamantyl (meth) acrylate, etc. Is mentioned. From the viewpoint of adhesion to a substrate or the like, 3-hydroxyadamantyl (meth) acrylate, 2- or 3-cyano-5-norbornyl (meth) acrylate, 2-cyanomethyl-2-adamantyl (meth) acrylate and the like are preferable.
The monomer which has a hydrophilic group may be used individually by 1 type, and may be used in combination of 2 or more type.

<Method for producing copolymer for lithography>
Hereinafter, a method for producing a resist copolymer will be described as a representative example of a method for producing a lithographic copolymer, but other lithographic copolymers can be similarly applied.
The resist copolymer can be obtained by radical polymerization. The polymerization method is not particularly limited, and a known method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method can be appropriately used.
In particular, the solution radical polymerization method is preferred from the viewpoint that the step of removing the monomer remaining after the completion of the polymerization reaction can be easily performed and the molecular weight of the polymer can be relatively easily lowered in order not to reduce the light transmittance. Among them, the drop polymerization method is more preferable from the viewpoint that a variation in average molecular weight, molecular weight distribution, etc. due to the difference in production lot is small and a reproducible polymer can be easily obtained.

  In the dropping polymerization method, the inside of the polymerization vessel is heated to a predetermined polymerization temperature, and then the monomer and the polymerization initiator are dropped into the polymerization vessel independently or in any combination. A monomer may be dripped only with a monomer, or may be dripped as a monomer solution in which a monomer is dissolved in a solvent. The polymerization vessel may be charged with a solvent in advance or may not be charged. When the solvent is not charged in advance in the polymerization vessel, the monomer or the polymerization initiator is dropped into the polymerization vessel in the absence of the solvent.

The polymerization initiator may be dissolved directly in the monomer, dissolved in the monomer solution, or dissolved only in the solvent. The monomer and the polymerization initiator may be dropped into the polymerization vessel after mixing in the same storage tank, or may be dropped from the independent storage tank into the polymerization container. Alternatively, they may be mixed immediately before being supplied from independent storage tanks to the polymerization vessel and dropped into the polymerization vessel. One of the monomers and the polymerization initiator may be dropped first, and then the other may be dropped with a delay, or both may be dropped at the same timing.
The dropping speed may be constant until the dropping is completed, or may be changed in multiple stages according to the consumption speed of the monomer or the polymerization initiator. The dripping may be performed continuously or intermittently.

In the case of using the dropping polymerization method based on the solution radical polymerization, a method of suppressing the formation of a high molecular weight body by increasing the supply rate of the polymerization initiator and / or monomer at the initial stage of polymerization can be used.
Generally, in the dropping polymerization method, when the monomer and the polymerization initiator are dropped at the same dropping time and at a uniform rate, a high molecular weight product tends to be formed at the initial stage of polymerization. Therefore, by increasing the supply rate of the polymerization initiator at the initial stage of polymerization, the decomposition of the polymerization initiator is promoted, radical generation / deactivation is constantly generated, and the monomer is dropped into the radical. Thus, the formation of a high molecular weight product in the initial stage of polymerization can be suppressed. Specifically, two or more kinds of dropping liquids are prepared, and a method of changing the supply rate of each dropping liquid in multiple stages, or a solvent and a polymerization initiator are partially or completely charged in advance in a polymerization vessel, Then, the method etc. of dripping the dripping liquid containing various monomers and / or the remaining polymerization initiator, etc. are mentioned.

In general, in the dropping polymerization method, when two or more monomers having different reactivity and a polymerization initiator are dropped at the same dropping time and at a uniform rate, the polymerization of the highly reactive monomer is first performed. As a result, the copolymer having a non-uniform composition tends to be included in the high molecular weight product generated particularly at the initial stage of polymerization.
As a method of suppressing the formation of a high molecular weight polymer having a non-uniform composition at the initial stage of polymerization, for example, according to the reactivity ratio of each monomer used for polymerization, a monomer is charged in advance in the reactor, There is a method for producing a polymer having a uniform composition by polymerizing in a steady state from the initial stage of polymerization.

  Furthermore, when the method for suppressing the formation of a high molecular weight body in the initial stage of polymerization and the method for suppressing the formation of a high molecular weight body having a non-uniform composition in the initial stage of polymerization are combined, Since coalescence can be obtained, it is preferable.

  According to the said manufacturing method, the dispersion | variation in the composition ratio and molecular weight of the structural unit in a copolymer tends to become small. When the variation in the composition ratio and molecular weight of the structural units is small, the solubility in a solvent is good, and high sensitivity is obtained when used in a resist composition.

<Evaluation method>
The evaluation method of the present invention includes the following steps:
(1) a step of preparing a test solution by dissolving a copolymer for lithography in a solvent;
(2) a step of measuring the scattering intensity in the particle size distribution of the test solution using a dynamic light scattering method;
(3) adding a poor solvent to the test solution and measuring a scattering intensity in a particle size distribution of the test solution after the poor solvent is added using a dynamic light scattering method;
(4) When the scattering intensity of an arbitrary peak (a) of the particle size distribution measured in the step (2) is used as a reference, the measurement is performed in the step (3) by adding a poor solvent. Obtaining a poor solvent addition amount required for the scattering intensity of the peak (a) to decrease to a predetermined intensity with respect to the reference;
(5) The process of evaluating the lithography characteristic of the composition containing the said copolymer for lithography by the difference in the said poor solvent addition density | concentration.

<(1) Process>
The test solution is prepared by dissolving a resist copolymer in a solvent. The solvent is preferably a good solvent. The content of the resist copolymer in the test solution is preferably 15% by mass to 25% by mass, and more preferably 18% by mass to 22% by mass. The resist copolymer is preferably completely dissolved in a good solvent.
In this evaluation method, by adding a poor solvent, the concentration of the copolymer relative to the solution is relatively increased, and a state of change approaching saturation from a concentration that dissolves well is observed. If the concentration is 15% by mass to 25% by mass, it does not dissociate too much into a saturated state, nor is it too close, so the change from a well-dissolved state to a saturated state due to the addition of a poor solvent is most easily observed.
In addition, in this evaluation method, the state of increase in particles due to the addition of a poor solvent is observed. If the polymer is not completely dissolved in the solvent, the increase in particles is caused by using the undissolved particles as nuclei. Solutions that may occur and are not completely dissolved are undesirable for the evaluation method.

The good solvent in this specification refers to a solvent that can completely dissolve the resist copolymer in a solvent amount of 5 mass times or less at room temperature (25 ° C.). In particular, it is preferable to use a solvent that can completely dissolve the resist copolymer with a solvent amount of 3 mass times or less. The good solvent used for the test solution may be a single solvent or a mixture of two or more. In the case of a mixed solvent, any solvent can be used as long as it satisfies the above-mentioned good solvent conditions after mixing.
In the present specification, “completely dissolved” refers to a transmittance measured using a wavelength at which a resist film formed using a resist copolymer dissolved in a solution does not exhibit transparency. Is 100%. For example, when the resist copolymer is an acrylic polymer, the wavelength in the visible light region is preferable as the measurement wavelength, and specifically, 380 nm to 780 nm is preferable.

  On the other hand, the poor solvent means a solvent that does not dissolve at all even when a 5 mass-fold amount of a single solvent is added to the resist copolymer and stirred at room temperature (25 ° C.). In particular, it is preferable to use a solvent that does not dissolve at all even when a 10 mass-fold amount of a single solvent is added. In the case of a mixed solvent, it can be used as a poor solvent as long as it satisfies the above poor solvent conditions after mixing.

As a good solvent, it can select from the well-known resist solvent used when preparing a resist composition suitably, and can use it. You may use individually by 1 type and may be used in combination of 2 or more type.
Specific examples of preferable good solvents include tetrahydrofuran, 1,4-dioxane, acetone, methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl lactate, ethyl lactate, butyl lactate, and γ-butyrolactone. Can be mentioned.

As the poor solvent, pentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, diethyl ether, diisopropyl ether, methanol, ethanol, isopropanol, water, and the like can be used. A poor solvent may be used individually by 1 type, and may be used in combination of 2 or more type.
In particular, when the resist copolymer to be evaluated is an acrylic copolymer, PGMEA (propylene glycol monomethyl ether acetate), ethyl lactate, THF (tetrahydrofuran) is used as a good solvent, and IPE (diisopropyl ether) is used as a poor solvent. , Hexane, heptane, and methanol are preferably used.

<(2) Process>
After the test solution is prepared, the scattering intensity in the particle size distribution of the test solution is measured using a dynamic light scattering method. In general, examples of the method for measuring the particle size distribution include a laser diffraction method, a centrifugal sedimentation method, an FFF method (Field Flow Fractionation), an electrical detection band method, and the like. Evaluation was performed using the dynamic light scattering method from the point where the measurement in the diameter and the solution state was possible.

  Although the measurement temperature of particle size distribution measurement is not specifically limited, 15 to 35 degreeC is preferable, More preferably, it is 20 to 30 degreeC. Since the solution viscosity is related to the particle size distribution, and the solution viscosity is sensitive to temperature, it is preferable to perform the measurement at a temperature close to room temperature where the temperature tends to be stable.

<(3) Process>
Next, after adding a poor solvent to the test solution, the scattering intensity in the particle size distribution of the test solution is measured using a dynamic light scattering method.

As in the step (2), the measurement temperature for the particle size distribution measurement is not particularly limited, but is preferably 15 ° C to 35 ° C, and more preferably 20 ° C to 30 ° C. Since the solution viscosity is related to the particle size distribution, and the solution viscosity is sensitive to temperature, it is preferable to perform the measurement at a temperature close to room temperature where the temperature tends to be stable.
The poor solvent is as described above.

<(4) Process>
Next, when the scattering intensity of an arbitrary peak (a) in the particle size distribution measured in the step (2) is used as a reference, the peak measured in the step (3) by adding a poor solvent A poor solvent addition amount required until the scattering intensity of (a) decreases to a predetermined intensity with respect to the reference is obtained.
The reason why the scattering intensity is reduced by gradually adding the poor solvent is that the addition of the poor solvent facilitates precipitation of a polymer having a high molecular weight or a non-uniform composition. This is probably because agglomeration or the like occurs and the particle size distribution changes.
The method for obtaining the amount of the poor solvent added is not particularly limited, but for example, it can be measured by the following method.

[Method for Determining Poor Solvent Addition Amount (M Value)]
The arbitrary peak intensity (a) of the particle size distribution measured in the steps (2) and (3) is not particularly limited, but from the viewpoint of quantification and reproducibility, the particle diameter showing the maximum scattering intensity. It is preferable to employ the peak (a).
Further, “predetermined intensity” in the case where the amount of anti-solvent added required for the scattering intensity of the peak (a) to be reduced to a predetermined intensity with respect to the reference is measured in the step (3). Is not particularly limited, but from the viewpoint of quantification and reproducibility, the strength is preferably 10% to 90%, preferably 40% to 60%, and more preferably 50% with respect to the above criteria.
Hereinafter, for one embodiment of the present invention, when the peak (a) in the particle diameter showing the maximum scattering intensity when no poor solvent is added is used as a reference, the peak (a) is converted into the reference by adding the poor solvent. The amount of addition of the poor solvent required to decrease to 50% (M value: mass%) will be described.

First, a resist copolymer test solution (for example, the copolymer concentration is 20% by mass) is prepared, and the particle size distribution is measured. From the obtained particle size distribution, the scattering intensity (S ₀ ) at the particle diameter R showing the maximum scattering intensity is obtained.

Subsequently, m% by mass of a poor solvent is added to the test solution, the mixture is sufficiently stirred, and the particle size distribution is measured. From the obtained particle size distribution, the scattering intensity S _m at the particle diameter R showing the maximum scattering intensity when no poor solvent is added is determined. Furthermore, S _m / S ₀ indicating a decrease in the scattering intensity at the particle size R due to the addition of the poor solvent is obtained.

Here, the addition amount m of the poor solvent is preferably 30% <S _m / S ₀ <70%, more preferably 10% <S _m / S ₀ <90%. It is good to do. Further, it is preferable to adjust the amount of m added so that m is preferably 4 points or more, more preferably 6 points or more in this range. These are for increasing the accuracy of evaluation by increasing the number of measurement points and widening the measurement range.
From the obtained data, the poor solvent addition amount (concentration) at which the scattering intensity at the particle size R becomes S _m / S ₀ = 50% by the addition of the poor solvent is determined, and this is referred to as M value (mass%). To do.
The M value varies depending on the physical properties of the copolymer contained in the test solution to be measured, the weight average molecular weight and composition of the copolymer, the concentration of the solution, and the like. It is preferable to use for comparison between different copolymers.

The M value correlates with the sensitivity when a resist copolymer is used as a resist composition, as shown in the Examples described later. That is, when there is no difference in the physical properties of the copolymer, the weight average molecular weight or composition of the copolymer, the larger the M value, the better the sensitivity. Therefore, sensitivity can be evaluated using the M value.
In addition, high sensitivity means that the alkali solubility after exposure of the resist composition is good. For example, development characteristics such as development defects (defects) and variations in pattern dimensions (LER). It is speculated that it is also good. That is, it is assumed that the high sensitivity means that the lithography characteristics such as the development characteristics are also good.

In addition, as shown in the examples described later, the component that easily causes an increase in particle size due to the addition of a poor solvent is a relatively high molecular weight component in the copolymer, and the composition of the structural unit is the design value. It is a component that deviates relatively greatly. From this, it is thought that this component is a component which increases the heterogeneity of a copolymer. The larger the M value in the present invention, the higher the uniformity in the copolymer. It is considered that the development characteristics such as sensitivity are improved because the uniformity is high.
Therefore, by using the evaluation method of the present invention, it is possible to evaluate not only the development characteristics of the resist composition but also the lithography characteristics that vary depending on the uniformity of the lithography copolymer.

  The lithographic copolymer having a large M value in the evaluation method of the present invention and the lithographic composition containing the copolymer have high molecular weight uniformity throughout the copolymer. Therefore, the lithography properties that are improved when the uniformity of the molecular weight of the copolymer is high are good.

  In the evaluation method of the present invention, by adding a poor solvent to relatively increase the concentration of the copolymer relative to the solution, a minute difference of each copolymer can be enlarged and detected. Even when comparing copolymers having differences and development characteristics, it is presumed that the influence of accuracy and error of the evaluation method can be suppressed, and as a result, highly accurate evaluation can be performed.

Moreover, the precipitation point (cloud point) of a copolymer can also be used for evaluation by the same principle.
For example, when a poor solvent is added to the resist copolymer test solution and the precipitation of the copolymer is visually confirmed, the poor solvent addition amount (% by mass) also correlates with the homogeneity of the copolymer. Therefore, it is possible to evaluate development characteristics and lithography characteristics. More quantitatively, when a poor solvent is added to the test solution of the resist copolymer, for example, until the transmittance at a wavelength of 450 nm is 85 ± 3%, the components precipitated at this time are among the copolymers. It is a component having a relatively high molecular weight and having a composition unit whose composition deviates relatively from the design value. From this, it is thought that this component is a component which increases the heterogeneity of a copolymer. And it means that the uniformity in this copolymer is so high that the cloud point in this invention is large. Therefore, like the M value, it is possible to evaluate the development characteristics and lithography characteristics of the resist composition by evaluating the uniformity of the copolymer.
Although not particularly limited, the cloud point evaluation is preferably performed at room temperature from the viewpoint of reproducibility and quantitativeness.

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.
In the following Production Examples 1 to 4, α-methacryloyloxy-γ-butyrolactone (α-GBLMA) and 3-hydroxyadamantyl methacrylate (HAdMA) are used as monomers having a polar group, and an acid leaving group is used. 1-Ethylcyclohexyl methacrylate (ECHMA) was used as a monomer having the same. The composition ratio of the structural units in the molecular design was α-GBLMA: ECHMA: HAdMA = 40: 40: 20 (mol%), and the polymerization procedure was changed to produce four types of copolymers AD. The same solvent and polymerization initiator were used.

  In addition, due to the difference in the polymerization procedure, it is possible to obtain a copolymer having a difference in the uniformity of the composition ratio of structural units in the entire copolymer, even if the copolymer has almost the same composition and molecular weight. .

[Production Example 1]
(Step 1A) In a flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel and a thermometer, 72.6 parts of ethyl lactate was placed under a nitrogen atmosphere, and the temperature of the hot water bath was raised to 80 ° C. while stirring. .
(Step 2A) α-GBLMA 30.6 parts, ECHMA 35.3 parts, HAdMA 21.2 parts, ethyl lactate 130.7 parts, dimethyl-2,2′-azobisisobutyrate (Wako Pure Chemical Industries, V- A mixed solution obtained by mixing 2.6 parts of 601 (product name) was dropped into the flask at a constant rate from a dropping funnel over 4 hours, and then a temperature of 80 ° C. was maintained for 3 hours.
(Step 3A) Next, the obtained reaction solution was added dropwise to a mixed solvent of methanol and water (methanol / water = 80/20 volume ratio) in an amount of about 7 times while stirring to precipitate a white gel. Obtained. The resulting precipitate was separated by filtration and again poured into a mixed solvent of methanol and water in an amount of about 7 times (methanol / water = 85/15 volume ratio). This was separated by filtration, collected, and dried under reduced pressure at 60 ° C. for about 40 hours to obtain a copolymer A powder.

[Production Example 2]
(Step 1A ′) The difference from Production Example 1 in Step 1A is that a flask equipped with two dropping funnels was used.
(Step 2A) The mixed solution was added dropwise in the same manner as in Step 2A of Production Example 1.
(Step 2B) Simultaneously with the start of dropping of the mixed solution in Step 2A, a mixed solution obtained by mixing 3.7 parts of ethyl lactate and 1.2 parts of V-601 (product name) was added from another dropping funnel over 0.1 hour. The solution was dropped into the flask, and the temperature of 80 ° C. was further maintained for 6.9 hours.
(Step 3A) The same operation as in step 3A of Production Example 1 was performed to obtain a powder of copolymer B.

[Production Example 3]
(Step 1C) Using a flask equipped with two dropping funnels, the monomer was charged into the flask before dropping. That is, in a flask equipped with a nitrogen inlet, a stirrer, a condenser, two dropping funnels and a thermometer, under a nitrogen atmosphere, 88.8 parts of ethyl lactate, 3.1 parts of α-GBLMA, 5.5 parts of ECHMA, 2.3 HAdMA2.3 The temperature of the hot water bath was raised to 80 ° C. while stirring.
(Step 2A ′) The composition of the mixed solution is different from Step 2A in Production Example 1. That is, a mixed solution in which 26.8 parts of α-GBLMA, 30.9 parts of ECHMA, 18.6 parts of HAdMA, 112.5 parts of ethyl lactate, and 1.9 parts of V-601 (product name) were mixed at a constant rate from a dropping funnel for 4 hours. And then dropped into the flask, and then maintained at 80 ° C. for 3 hours.
(Step 2B ′) The composition of the mixed solution is different from Step 2B of Production Example 2. That is, simultaneously with the start of dropping of the mixed solution in Step 2A ′, the mixed solution in which 1.8 parts of ethyl lactate and 0.7 part of V-601 (product name) were mixed was added to the flask over another 0.1 hour from another dropping funnel. It was dripped in and the temperature of 80 degreeC was further hold | maintained for 6.9 hours.
(Step 3A) The same operation as in step 3A of Production Example 1 was performed to obtain a powder of copolymer C.

[Production Example 4]
(Step 1C) In the same manner as in Step 1C of Production Example 3, a monomer was charged into the flask before dropping.
(Step 2A ″) The content of ethyl lactate and V-601 (product name) is different from Step 2A ′ of Production Example 3. That is, 26.8 parts of α-GBLMA, 30.9 parts of ECHMA, 18.6 parts of HAdMA, A mixed solution in which 110.3 parts of ethyl lactate and 0.7 parts of V-601 (product name) are mixed is dropped into the flask at a constant rate from a dropping funnel over 4 hours, and then maintained at a temperature of 80 ° C. for 3 hours. did.
(Step 2B ″) The contents of ethyl lactate and V-601 (product name) are different from those of Step 2B ′ of Production Example 3. That is, simultaneously with the start of dropping of Step 2A ″, 4.0 parts of ethyl lactate, V A mixed solution in which 1.4 parts of -601 (product name) was mixed was dropped into the flask over another 0.1 hour from another dropping funnel, and the temperature of 80 ° C. was further maintained for 6.9 hours.
(Step 3A) The same operation as in step 3A of Production Example 1 was performed to obtain a powder of copolymer D.

In Production Examples 5 and 6 below, α-methacryloyloxy-γ-butyrolactone (α-GBLMA) and 3-hydroxyadamantyl methacrylate (HAdMA) are used as monomers having a polar group, and an acid leaving group is used. 2-Methyl-2-adamantyl methacrylate (MAdMA) was used as the monomer. The composition ratio of the structural units in the molecular design was α-GBLMA: ECHMA: HAdMA = 45: 35: 20 (mol%), and two types of copolymers E and F were produced by changing the polymerization procedure. The same solvent and polymerization initiator were used. Copolymers A and E, D and F are manufactured by the same process.

[Production Example 5]
(Step 1A) A flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel and a thermometer was charged with 76.7 parts of ethyl lactate under a nitrogen atmosphere, and the temperature of the hot water bath was raised to 80 ° C. while stirring. .
(Step 2A) α-GBLMA 35.6 parts, MAdMA 37.6 parts, HAdMA 18.9 parts, ethyl lactate 138.1 parts, dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, V- A mixed solution in which 2.8 parts of 601 (product name) were mixed was dropped from a dropping funnel into the flask at a constant rate over 4 hours, and then a temperature of 80 ° C. was maintained for 3 hours.
(Step 3A) Next, the obtained reaction solution was added dropwise to a mixed solvent of methanol and water (methanol / water = 80/20 volume ratio) in an amount of about 7 times while stirring to precipitate a white gel. Obtained. The obtained precipitate was separated by filtration and again poured into a mixed solvent of methanol and water in an amount of about 7 times (methanol / water = 9/1 volume ratio). This was filtered and collected, and dried under reduced pressure at 60 ° C. for about 40 hours to obtain a copolymer E powder.

[Production Example 6]
(Step 1C) Using a flask equipped with two dropping funnels, the monomer was charged into the flask before dropping. That is, in a flask equipped with a nitrogen inlet, a stirrer, a condenser, two dropping funnels, and a thermometer, 93.9 parts ethyl lactate, 3.4 parts α-GBLMA, 6.1 parts MAdMA, HAdMA 2.0 under a nitrogen atmosphere. The temperature of the hot water bath was raised to 80 ° C. while stirring.
(Step 2A ″) The composition of the mixed solution is different from Step 2A in Production Example 5. That is, 31.1 parts of α-GBLMA, 32.9 parts of MAdMA, 16.5 parts of HAdMA, 116.5 parts of ethyl lactate, V-601 (Product name) A mixed solution in which 0.6 part was mixed was dropped from a dropping funnel into the flask at a constant rate over 4 hours, and then a temperature of 80 ° C was maintained for 3 hours.
(Step 2B ″) Simultaneously with the start of dropping of the mixed solution in Step 2A, a mixed solution obtained by mixing 4.3 parts of ethyl lactate and 1.4 parts of V-601 (product name) was added from another dropping funnel over 0.1 hour. Then, the solution was dropped into the flask, and the temperature of 80 ° C. was further maintained for 6.9 hours.
(Step 3A) The same operation as in step 3A of Production Example 5 was performed to obtain a powder of copolymer F.

  In the following Production Examples 7 and 8, benzyl methacrylate (BzMA) as a monomer having a light-absorbing group, 2-hydroxyethyl methacrylate (HEMA) as a monomer having a reactive functional group, and a monomer having a polar group Α-methacryloyloxy-γ-butyrolactone (α-GBLMA) was used. The composition ratio of the structural units in the molecular design was BzMA: HEMA: α-GBLMA = 25: 25: 50 (mol%), and the two kinds of copolymers G and H were produced by changing the polymerization procedure. The same solvent and polymerization initiator were used.

[Production Example 7]
(Step 1A) In a flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel and a thermometer, 61.9 parts of propylene glycol monomethyl ether (PGME) is placed under a nitrogen atmosphere, and the temperature of the hot water bath is adjusted while stirring. Raised to 80 ° C.
(Step 2A) 19.8 parts of BzMA, 16.2 parts of HEMA, 38.3 parts of α-GBLMA, 111.5 parts of PGME, dimethyl-2,2′-azobisisobutyrate (V-601 manufactured by Wako Pure Chemical Industries, Ltd. Product name)) A mixed solution in which 6.7 parts were mixed was dropped from a dropping funnel into the flask at a constant rate over 4 hours, and then a temperature of 80 ° C. was maintained for 3 hours.
(Step 2G) After holding, 50% by mass of PGME of the reaction solution was added to the flask to dilute the reaction solution.
(Step 3A) Next, the obtained reaction solution was added dropwise to about 4 times amount of isopropyl ether (IPE) while stirring to obtain a white gel-like precipitate. This was collected by filtration and dried under reduced pressure at 60 ° C. for about 40 hours to obtain a copolymer G powder.

[Production Example 8]
(Step 1H) Under a nitrogen atmosphere, 98.3 parts of PGME was placed in a flask equipped with a nitrogen inlet, a stirrer, a condenser, two dropping funnels and a thermometer, and the temperature of the hot water bath was raised to 80 ° C. while stirring. .
(Step 2A ″) The composition of the mixed solution is different from Step 2A of Production Example 7. That is, 17.8 parts of BzMA, 14.6 parts of HEMA, 34.5 parts of α-GBLMA, 67.8 parts of PGME, V-601 (Product) Name) A mixed solution in which 2.1 parts were mixed was dropped from a dropping funnel into the flask at a constant rate over 4 hours, and then a temperature of 80 ° C. was maintained for 3 hours.
(Step 2H) Simultaneously with the start of dropping of the mixed solution in Step 2A, 2.1 parts of BzMA, 1.8 parts of HEMA, 2.9 parts of α-GBLMA, 5.9 parts of PGME, and 2.1 parts of V-601 (product name) are mixed. The mixed solution was dropped into the flask from another dropping funnel over 0.5 hours, and the temperature of 80 ° C. was further maintained for 6.5 hours.
(Step 2G) After holding, 50% by mass of PGME of the reaction solution was added to the flask to dilute the reaction solution.
(Step 3A) A powder of copolymer H was obtained by performing the same operation as in step 3A of Production Example 7.

(Weight average molecular weight of resist copolymer)
The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the copolymers A to H obtained in Production Examples 1 to 8 were measured by the following methods.
About 20 mg of sample was dissolved in 5 mL of THF and filtered through a 0.5 μm membrane filter to prepare a sample solution. This sample solution was prepared by Tosoh gel permeation chromatography (GPC) apparatus: HCL-8220 ( Product name), the weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured to obtain the molecular weight distribution (Mw / Mn). In this measurement, the separation column was made by Showa Denko, Shodex GPC LF-804L (product name) in series, the solvent was THF (tetrahydrofuran), the flow rate was 1.0 mL / min, and the detector was a differential. Polystyrene was used as a standard polymer with a refractometer, a measurement temperature of 40 ° C., and an injection amount of 0.1 mL. The measurement results are shown in Table 1, Table 3, and Table 5.

(Composition ratio of structural units in resist copolymer)
The composition ratio (unit: mol%) of each structural unit derived from each monomer in the resist copolymer was determined by ¹ H-NMR measurement.
In this measurement, a JNM-GX270 type superconducting FT-NMR manufactured by JEOL Ltd. was used, and a sample solution of about 5% by mass (solvents were deuterated dimethyl sulfoxide (A to F), deuterated chloroform (G , H)) was put into a sample tube having a diameter of 5 mmφ, and ¹ H was integrated 64 times in an observation frequency of 270 MHz and a single pulse mode. The measurement temperature was 60 ° C. when the measurement solvent was deuterated dimethyl sulfoxide, and 40 ° C. when deuterated chloroform was used. The measurement results are shown in Table 1, Table 3, and Table 5.

(Evaluation by particle size distribution measurement)
With respect to the polymers A to F obtained in Production Examples 1 to 6, the copolymer concentration was adjusted to 20 mass% PGMEA (propylene glycol monomethyl ether acetate), and then sufficiently stirred to obtain a uniform test solution. The test solution was filtered through a 0.5 μm filter (for organic solvent), and then dynamic light scattering measurement was performed at 25.0 ° C. From the obtained particle size distribution, the scattering intensity (S ₀ ) at the particle diameter R showing the maximum scattering intensity was determined.
Subsequently, to the test solution, m% by mass of a poor solvent (heptane) was added to the test solution, and the mixture was sufficiently stirred to perform dynamic light scattering measurement. From the obtained particle size distribution, the scattering intensity S _m at the particle diameter R that showed the maximum scattering intensity when no poor solvent was added was determined. Furthermore, to determine the S _{m /} S ₀ shown in scattering intensity in particle diameter R, the reduction with a poor solvent addition.
In the range of 20% <S _m / S ₀ <70%, the poor solvent addition amount m was measured by taking 8 points, and from the obtained data, the poor solvent addition amount (S _m / S ₀ = 50%) ( Density | concentration) was calculated | required and M (mass%) was calculated | required.
Regarding the polymers G and H obtained in Production Examples 7 and 8, THF (tetrahydrofuran) was used as a solvent and IPE (isopropyl ether) was used as a poor solvent.
The results are shown in Table 2, Table 4, and Table 6.

(Cloud point evaluation)
Regarding the polymers A to F obtained in Production Examples 1 to 6, a 20% by mass PGMEA (propylene glycol monomethyl ether acetate) solution was prepared and sufficiently stirred to obtain a uniform test solution. While stirring this test solution, a poor solvent (heptane) was added (at 25.0 ° C.) until the transmittance at a wavelength of 450 nm was 85 ± 3%, and the amount of poor solvent added up to this point (cloud point) ( Mass%).
Regarding the polymers G and H obtained in Production Examples 7 and 8, THF (tetrahydrofuran) was used as a solvent and IPE (isopropyl ether) was used as a poor solvent.
The results are shown in Table 2, Table 4, and Table 6.

(Sensitivity evaluation)
Resist compositions for lithography were prepared using the resist copolymers A to F, respectively, and the sensitivity when dry lithography was performed using the resist compositions was measured by the following method.
(Preparation of resist composition)
The following compounding components were mixed to obtain a resist composition.
Copolymer for resist: 10 parts,
Photoacid generator (manufactured by Midori Chemical Co., Ltd., product name: TPS-105, triphenylsulfonium triflate): 0.2 part,
Leveling agent (Nihon Unicar Co., Ltd., product name: L-7001): 0.2 parts,
Solvent (PGMEA): 90 parts.

(Dry lithography)
The resist composition obtained above was spin-coated on a 6-inch silicon wafer and pre-baked (PB) at 120 ° C. for 60 seconds on a hot plate to form a thin film having a thickness of 300 nm. Using an ArF excimer laser exposure apparatus (manufactured by RISOTEC Japan, product name: VUVES-4500), exposure was changed for 18 shots. One shot is the entire surface exposure for a rectangular area of 10 mm × 10 mm. Next, after post-baking (PEB) at 110 ° C. for 60 seconds, using a resist development analyzer (product name: RDA-790, manufactured by RISOTEC Japan), 2.38% tetrahydroxide at 23.5 ° C. Development was carried out with a methylammonium aqueous solution for 65 seconds, and the change over time in the resist film thickness during development was measured. For each exposure amount, the ratio of the remaining film thickness at the time of development for 60 seconds with respect to the initial film thickness (hereinafter referred to as the remaining film ratio, unit:%) was determined.

A curve plotting the logarithm of the exposure amount (mJ / cm ² ) and the residual film thickness ratio (hereinafter referred to as the residual film ratio) (%) when developed for 60 seconds with respect to the initial film thickness, based on the obtained data (Hereinafter referred to as exposure amount remaining film rate curve) was prepared, and the value of exposure amount (mJ / cm ² ) (hereinafter referred to as Eth) at which the exposure amount remaining film rate curve intersected with the remaining film rate 0% was determined. Eth is a necessary exposure amount for achieving a remaining film ratio of 0% and represents sensitivity. The smaller the Eth, the higher the sensitivity. The results are shown in Tables 2 and 4.

[Solubility evaluation]
A solution for solubility evaluation was prepared using each of the above copolymers G and H for lithography, and the temperature of the solution was room temperature (25 ° C.). Using UV-3100PC (product name) manufactured by Shimadzu Corporation as an ultraviolet-visible spectrophotometer, the measurement solution is put into a quartz square cell having an optical path length of 10 mm, and the transmittance at a wavelength of 450 nm is measured. Sex evaluation was performed. The higher the transmittance, the better the solubility, leading to a reduction in lithographic performance variation in the surface when the film is coated on the substrate.
(Solution preparation for solubility evaluation)
The following formulation components were mixed to obtain an evaluation solution.
Lithographic copolymer: 20 parts,
Solvent 1 (THF): 80 parts
Solvent 2 (IPE): 8 parts.

  Table 1 below shows the physical properties of the polymers A to D.

[Examples 1 to 4]
Table 2 below shows the evaluation results (poor solvent addition amount) and the cloud point evaluation results (poor solvent addition amount until reaching the cloud point) by measuring the particle size distribution of the polymers A to D.

  Table 3 below shows the physical properties of the polymers E and F.

[Examples 5 and 6]
The evaluation results (M value: poor solvent addition amount) and the cloud point evaluation results (poor solvent addition amount until reaching the cloud point) by the particle size distribution measurement of the polymers E and F are shown in Table 4 below.

  Table 3 below shows the physical properties of the polymers E and F.

[Examples 7 and 8]
Table 6 below shows evaluation results (M value: poor solvent addition amount) and cloud point evaluation results (poor solvent addition amount until reaching the cloud point) of the polymers G and H by particle size distribution measurement.

As shown in Table 1, the copolymers A to D are copolymers having substantially the same composition and molecular weight, but are copolymers having different polymerization methods. These have differences in the uniformity of the composition ratio in the copolymer due to the difference in the polymerization method.
Similarly, as shown in Table 3, the above-mentioned copolymers E and F are substantially the same composition / molecular weight copolymers, but are copolymers having different polymerization methods. These have differences in the uniformity of the composition ratio in the copolymer due to the difference in the polymerization method.
Similarly, as shown in Table 5, the copolymers G and H are copolymers having substantially the same composition and molecular weight, but are copolymers having different polymerization methods. These have differences in the uniformity of the composition ratio in the copolymer due to the difference in the polymerization method.
In addition, in the evaluation by the particle size distribution measurement or the cloud point evaluation, it is shown that the composition ratio in the copolymer has uniformity and the like as the addition amount of the poor solvent increases.
As shown in Table 2, Table 4 and Table 6, in comparison between the copolymers, evaluation results (poor solvent addition amount), cloud point evaluation results (cloud point) of these methods of the present invention. (The amount of poor solvent added until reaching) is correlated with development defects, Eth related to LER, or transmittance related to solubility, and can indirectly evaluate lithography properties It was confirmed.
From these results, it was confirmed that the method of the present invention can indirectly evaluate the lithography characteristics with high accuracy.

Claims (1)

Lithographic copolymer evaluation method comprising the following steps:
(1) a step of preparing a test solution by dissolving a copolymer for lithography in a solvent;
(2) a step of measuring the scattering intensity in the particle size distribution of the test solution using a dynamic light scattering method;
(3) adding a poor solvent to the test solution and measuring a scattering intensity in a particle size distribution of the test solution after the poor solvent is added using a dynamic light scattering method;
(4) When the scattering intensity of an arbitrary peak (a) of the particle size distribution measured in the step (2) is used as a reference, the measurement is performed in the step (3) by adding a poor solvent. Obtaining a poor solvent addition amount required for the scattering intensity of the peak (a) to decrease to a predetermined intensity with respect to the reference;
(5) The process of evaluating the lithography characteristic of the composition containing the said copolymer for lithography by the difference in the said poor solvent addition amount.